This invention relates to froth flotation.
Froth flotation is one of the most important processes currently used to extract the desired mineral from the accompanying unwanted gangue minerals in a pulp. Froth flotation is a means of treating a pulp of finely ground ores so that it yields the valuable or desired mineral in a concentrate that will be amenable to further processing. The process involves the imparting of a water-repellant character to the wanted mineral particles by chemicals that are called collectors or promotors. Under favourable conditions, these chemically coated particles become attached to the air that is bubbled through a pulp and will thus float on the surface.
The surface tension of the pulp is reduced by a second chemical called a frother, thereby producing a stabilised froth containing the wanted mineral particles on the surface of the pulp. This froth is skimmed off yielding a concentrate in which the desired mineral is present in much higher percentage than in the original ore.
Froth flotation is also used to separate one component of a mineral mixture from another component of that mineral mixture.
There are a number of sulphide minerals which contain gold. Examples of these minerals are arsenopyrite, pyrrhotite and pyrite. In arsenopyrite and pyrrhotite, the gold is in occluded form which makes it difficult to be reached by conventional leaching methods. On the other hand, the gold in pyrite is generally present in a condition in which it is readily amenable to leaching by conventional methods. These various sulphide minerals generally exist together. The fact that the gold exists in the various components of the mixture in a different form, complicates the recovery of the gold from such mixtures. It is thus desirable to separate arsenopyrite and pyrrhotite from pyrite.